Invasive biosensor alignment and retention

ABSTRACT

Examples of invasive biosensor alignment and retention features and methods are described. One example biosensor includes a housing comprising: a first surface defining a first opening, and a second surface opposite the first surface, the second surface defining a second opening, the first and second openings defining a substantially unobstructed pathway through the housing; a biosensor wire partially disposed within the housing and having an exterior portion extending through the first opening; a hollow insertion needle positioned within the pathway and extending through the first opening, the hollow insertion needle at least partially encircling the biosensor wire; and a biosensor retention feature collapsible against the first surface of the housing, the biosensor retention feature encircling and contacting the hollow insertion needle.

FIELD

The present application generally relates to invasive biosensors andmore generally relates to invasive biosensor alignment and retention.

BACKGROUND

Wearable invasive biosensors, such as continuous glucose monitors(“CGMs”), employ sensor wires that are inserted into a wearer's skin tomeasure analytes, such as glucose levels. Because sensor wires typicallyhave a small diameter and may not be able to puncture a wearer's skinwithout bending or breaking, a needle is used to create a puncture woundthrough which the sensor wire is inserted. In some cases, the needle isinserted through an opening in the biosensor and axially aligned withthe sensor wire so that, when the CGM is pressed against the wearer'sskin, the needle creates the puncture wound and the sensor wire isinserted through the puncture. The needle is then withdrawn, leaving thesensor wire in place.

SUMMARY

Various examples are described for invasive biosensor alignment andretention. One example wearable biosensor includes a housing comprising:a first surface defining a first opening, and a second surface oppositethe first surface, the second surface defining a second opening, thefirst and second openings defining a substantially unobstructed pathwaythrough the housing; a biosensor wire partially disposed within thehousing and having an exterior portion extending through the firstopening; a hollow insertion needle positioned within the pathway andextending through the first opening, the hollow insertion needle atleast partially encircling the biosensor wire; and a biosensor retentionfeature collapsible against the first surface of the housing, thebiosensor retention feature encircling and contacting the hollowinsertion needle.

One example method for providing invasive biosensor alignment andretention includes providing a housing comprising: a first surfacedefining a first opening, and a second surface opposite the firstsurface, the first surface defining a second opening, the first andsecond openings defining a substantially unobstructed pathway throughthe housing; positioning a biosensor wire within the housing and a firstportion of the biosensor wire extending through the first opening;inserting a hollow insertion needle into the pathway through theunobstructed pathway from the second opening and through the firstopening, the hollow insertion needle at least partially encircling thefirst portion of the biosensor wire; applying a biosensor retentionfeature to the hollow insertion needle, the biosensor retention featureencircling and contacting the hollow insertion needle and configured tocollapse against the bottom surface of the housing.

Another example wearable biosensor includes a housing comprising: afirst surface defining a first opening, and a second surface oppositethe first surface, the second surface defining a second opening, thefirst and second openings defining a substantially unobstructed pathwaythrough the housing; a biosensor wire partially disposed within thehousing and having an exterior portion extending through the firstopening; a hollow insertion needle positioned within the pathway andextending through the first opening coaxially aligned with the exteriorportion of the biosensor, the hollow insertion needle at least partiallyencircling the exterior portion of the biosensor wire; and means formaintaining coaxial alignment between the hollow insertion needle andthe biosensor wire coupled to a portion of the hollow insertion needlecoaxially aligned with the exterior portion of the biosensor wire.

An example method for applying a wearable biosensor includes obtaining awearable biosensor comprising: a housing comprising a first surfacedefining a first opening, and a second surface opposite the firstsurface, the second surface defining a second opening, the first andsecond openings defining a substantially unobstructed pathway throughthe housing; a biosensor wire partially disposed within the housing andhaving an exterior portion extending through the first opening; a hollowinsertion needle positioned within the pathway and extending through thefirst opening, the hollow insertion needle at least partially encirclingthe biosensor wire; and a biosensor retention feature collapsibleagainst the first surface of the housing, the biosensor retentionfeature encircling and contacting the hollow insertion needle; applyingthe wearable biosensor to a wearer's skin comprising: inserting thehollow insertion needle into the wearer's skin through a puncture,inserting the biosensor wire through the puncture, and pressing thehousing against the wearer's skin and collapsing the biosensor retentionfeature against the housing; and withdrawing the hollow insertion needlefrom the wearer's skin and the housing.

These illustrative examples are mentioned not to limit or define thescope of this disclosure, but rather to provide examples to aidunderstanding thereof. Illustrative examples are discussed in theDetailed Description, which provides further description. Advantagesoffered by various examples may be further understood by examining thisspecification.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of this specification, illustrate one or more certain examples and,together with the description of the example, serve to explain theprinciples and implementations of the certain examples.

FIGS. 1A-1E show an example invasive biosensor and insertion needle andretention feature;

FIGS. 2A-2B show an example biosensor alignment and retention featureaccording to this disclosure;

FIG. 3 shows an example biosensor alignment and retention featureaccording to this disclosure;

FIGS. 4A-4B show an example biosensor alignment and retention featureaccording to this disclosure;

FIGS. 5A-5B show an example biosensor alignment and retention featureaccording to this disclosure;

FIGS. 6-7 show example manufacturing techniques for alignment ofbiosensors and insertion needles according to this disclosure;

FIGS. 8A-8B show an example method for assembling a biosensor alignmentand retention feature;

FIGS. 9A-9B show an example method for assembling a biosensor alignmentand retention feature;

FIGS. 10A-10B show an example method for assembling a biosensoralignment and retention feature;

FIGS. 11A-11B show an example biosensor alignment and retention feature;

FIGS. 12A-12B show an example biosensor alignment and retention feature;

FIGS. 13A-13B show an example biosensor alignment and retention feature;

FIGS. 14A-14C show an example biosensor alignment and retention feature;

FIG. 15 shows an example method for assembling a biosensor alignment andretention feature; and

FIG. 16 shows an example method for applying a wearable biosensor havinga biosensor alignment and retention feature.

DETAILED DESCRIPTION

Examples are described herein in the context of invasive biosensoralignment and retention. Those of ordinary skill in the art will realizethat the following description is illustrative only and is not intendedto be in any way limiting. Reference will now be made in detail toimplementations of examples as illustrated in the accompanying drawings.The same reference indicators will be used throughout the drawings andthe following description to refer to the same or like items.

In the interest of clarity, not all of the routine features of theexamples described herein are shown and described. It will, of course,be appreciated that in the development of any such actualimplementation, numerous implementation-specific decisions must be madein order to achieve the developer's specific goals, such as compliancewith application- and business-related constraints, and that thesespecific goals will vary from one implementation to another and from onedeveloper to another.

An invasive biosensor includes one or more sensing components that areinserted into a person's body, such as through the person's skin, andmay measure analytes to determine information, such as glucose levels.For example, a continuous glucose monitor (“CGM”) may be applied to andworn by a person (the “wearer”) for a period of time to monitor thewearer's glucose levels. This example CGM includes a sensor wire that isinserted into the wearer's skin to access interstitial fluid and senseglucose levels. However, because the sensor wire is fragile at theintended thickness/diameter, 100 micrometers (or “microns”) in thisexample, a needle is used to puncture the skin and insert the sensorwire. The example CGM is coupled to an insertion device with a hollowinsertion needle, which is positioned coaxially with the CGM sensorwire, which is positioned within the hollow portion of the insertionneedle. When the wearer applies the CGM, she will puncture her skinusing the insertion needle and the sensor wire will follow the needleinto the puncture. After the CGM sensor wire has been inserted into thepuncture and the CGM is attached to the wearer's skin the wearerretracts the needle, leaving the sensor wire under the skin and the CGMin place.

Referring to FIGS. 1A-1D, these figures show different views of theexample CGM 100, which has a housing 110 and a sensor wire 120. As canbe seen in FIG. 1A, the sensor wire 120 extends out of the housing 110so that it may be inserted into the wearer's skin and the housing can110 be affixed to the wearer's skin

To apply the CGM 100, and as shown in FIG. 1B, a needle 130 (alsoreferred to as an “insertion needle”) is inserted through a hole in theupper surface of the CGM 100, through a cavity formed within theinterior of the CGM 100 to accommodate the needle 130 and the sensorwire 120, and through a hole in the lower surface of the CGM 100. Theneedle 130 is inserted so that it aligns axially with the sensor wire120. Thus, the CGM 100, the needle 130, and the sensor wire 120 can allbe pressed against the wearer's skin to apply the CGM 100 in a singlemotion. As the CGM 100 is pressed against the wearer's skin, the needle130 punctures the skin and the sensor wire 120 is pressed through thepuncture. The CGM 100 is then pressed against the wearer's skin, whereit remains, e.g., via pressure-sensitive adhesive (“PSA”). The needle130 is then withdrawn, leaving the CGM 100 and sensor wire 120 in place.

FIGS. 1C-1D illustrate how the needle 130 and the sensor wire 120 engageto allow substantially simultaneous insertion into the wearer's skin.The insertion needle 130 in this example is hollow and has an opencross-section as illustrated in FIG. 1D, which may be referred to ashaving a “C” or “U” shape, and extends slightly beyond the end of thesensor wire 120. The amount by which the needle extends beyond thesensor wire is not material; though puncturing the wearer's skin to adepth beyond what is needed to insert the sensor wire 120 should beavoided as causing unnecessary pain or trauma to the wearer. As can beseen in FIG. 1D, the needle's cross section has a larger diameter thanthe sensor wire 120. By orienting and positioning the needle 130 toenclose the sensor wire 120 within its hollow cross-section, the needle130 and sensor wire 120 can be positioned co-axially and thus, when thewearer presses needle 130 into the wearer's skin to create a puncture,the sensor wire 120 can immediately travel into the puncture created bythe needle 130.

However, in some examples, the CGM 100 may be packaged with theinsertion needle 130 already coupled to the CGM 100. Thus, the user mayobtain a new CGM 100 and not be required to insert the needle throughthe CGM 100 to them apply the CGM 100. However, because the packaged CGM100 may be subjected to various forces during manufacturing, packaging,and transportation, the sensor wire 120 and needle 130 may becomeunaligned. For example, the sensor wire 120 may be jolted or bent out ofthe C-shaped cross-section, such as following the package being dropped.To help maintain the co-axial arrangement of the needle 130 and sensorwire 120 while subcutaneously inserting the sensor wire 120, the CGM 100has a sensor alignment and retention feature coupled to its bottomsurface.

Referring now to FIG. 1E, FIG. 1E illustrates the bottom surface of theCGM 100 with an attached sensor alignment and retention feature 140 (or“retention feature”). The retention feature 140, in this example,includes a portion adhered to the bottom surface of the CGM 100, such asby a PSA. In addition, the retention feature has an extendible portion142 that has been cut and spirals upwards around the insertion needle130. During manufacturing, the extendible portion 142 has been pulledaway from the bottom surface of the CGM 100 to form a spiral shape. Thetip of the cut portion 142 contains a close fitting hole which fitsaround and engages with the needle 130, thereby helping to prevent thesensor wire 120 from dislodging from within the cross-section of thehollow insertion needle 130. When the CGM 100 is later applied to awearer's skin, the extendible portion 142 collapses and flattens backagainst bottom surface of the CGM 100 as it is pressed against thewearer's skin, before ultimately lying flush against the bottom surfaceof the CGM 100. Thus, the extendible portion 142 helps maintain co-axialalignment between the sensor wire 120 and insertion needle 130, whilenot affecting the CGM's insertion procedure.

This illustrative example is given to introduce the reader to thegeneral subject matter discussed herein and the disclosure is notlimited to this example. The following sections describe variousadditional non-limiting examples and examples of systems and methods forinvasive biosensor alignment and retention. FIGS. 2A-14B illustratefurther examples of means for maintaining coaxial alignment between ahollow insertion needle and a biosensor wire and are described in moredetail below.

Referring now to FIGS. 2A-2B, FIGS. 2A-2B show an example sensoralignment and retention feature 210 according to this disclosure. Theretention feature 210 in this example includes a pad (or backingmaterial) 220 that may be used to couple the retention feature 210 to abiosensor, such as a CGM. The pad 220 may be shaped during themanufacturing process to correspond to the shape of a lower surface of abiosensor, or to a portion of such a shape. The retention feature 210also includes an extendable portion 230 that may be extended duringmanufacturing, or when an insertion needle is inserted through the CGM,to form a spiral shaped feature to retain a co-axial alignment between asensor wire and insertion needle. In FIG. 2A, the extendable portion hasnot yet been extended and thus remains flush with the pad 220. Thishelps illustrate the shape of the cut used to form the cut portion 230and enable extension of the cut portion to create the spiral shape.

In this example and during the manufacturing process, the pad 220 isformed of a polyurethane foam, but may be constructed of othermaterials, such as cloth, silicone, etc. The extendable portion 230 inthis example is formed from a different piece of material than the pad220 and is coupled to the pad by an adhesive. However, in some examples,the extendable portion 230 may be formed from the same piece of materialas the pad 220. In some examples, as will be discussed in more detailbelow with respect to FIGS. 6-10, a pad may be formed from multiplelayers coupled to each other. The extendable portion 230 may be formedfrom any suitable material, including polyurethane foam, silicone, etc.Further, in some examples, the retention feature may not include the pad220, but may instead only include the cut portion 230.

FIG. 2B illustrates the retention feature 210 affixed to a lower surfaceof an invasive biosensor 200. As can be seen, the pad 220 generallycorresponds to the shape of the bottom surface of the biosensor 200,though it does not cover the entire bottom portion in this example. Itshould be appreciated that the pad 220 can be any suitable size andshape, depending on the application. For example, during themanufacturing process, the pad 220 may be shaped and sized to match theshape and size of the bottom surface of the biosensor 200. In someexamples the pad 220 may extend beyond one or more edges of the bottomsurface of the biosensor 200, or may only cover a portion of the bottomsurface of the biosensor 200.

Referring now to FIG. 3, FIG. 3 shows an example sensor alignment andretention feature 310 (or just “retention feature”) according to thisdisclosure. In this example, the retention feature 310 comprises an“accordion” shape. During the manufacturing process, a length ofmaterial has been folded back on itself multiple times and a hole havinga diameter a few tens of microns wider than the needle has been cutthrough the material to engage with and encircle the insertion needle320. By engaging and encircling the insertion needle 320 in thisexample, a sensor wire positioned within the hollow portion of theneedle may be retained. In the event of a shock or force applied to thesensor wire, it may be retained in place within the hollow portion ofthe needle by the retention feature. Further, when the biosensor 300 isapplied to the wearer, the retention feature 310 may fold and collapseagainst the bottom surface of the biosensor 300.

While the example shown in FIG. 3 does not include a pad, such asdiscussed above with respect to FIGS. 2A-2B, in some examples, theretention feature may also include or be coupled to a pad. As discussedabove with respect to the examples of FIGS. 2A-2B, any suitable pad maybe employed. Further, the retention feature 310 may be separatelyconstructed and then coupled to a pad, or may be formed from the samepiece of material as the pad.

Referring now to FIGS. 4A-4B, FIGS. 4A-4B show an example sensoralignment and retention feature 420 (or just “retention feature”)according to this disclosure. In this example, the retention feature 420is coupled to a pad 410 that may be affixed to a lower surface of abiosensor, such as biosensor 400 shown in FIG. 4B. The retention feature420 in this example has a central feature 424 that engages with andencircles the insertion needle 430 of a biosensor 400. In the exampleshown in FIG. 4A, the central feature 424 does not yet have an opening,such as a hole or slits (e.g., in an “|”, “X”, or “*” shape), cut in itto accommodate the insertion needle 430; however, the opening may be cutat any suitable point during the manufacturing process or it may becreated when an insertion needle is inserted through the CGM andretention feature, which may occur during the manufacturing process orat the time the CGM is applied by the wearer.

In addition to the central feature 424, the example retention feature420 includes two legs 422 a-b. Each leg 422 a-b has two ends, one ofwhich is coupled to a pad 410, or if no pad is used, to a ring or otherfeature that may be affixed to the bottom surface of a biosensor 400.The other end of each leg 422 a-b is coupled to the central feature 424.In this example, the legs 422 a-b attach at opposite sides of thecentral feature 424 and each then couple at a respective point on thepad 410 substantially 180 degrees around the central feature 424, i.e.,180 degrees offset from each other. In different examples, the legs maycouple at different locations on the pad 410 relative to coupling pointson the central feature 424, such as at 90 degrees offset, 120 degreesoffset, etc. Further, while two legs 422 a-b are shown in this example,in some examples, more than two legs may be employed. The two legs 422a-b allow the central feature 424 to extend away from the biosensor toengage with and encircle the insertion needle 430 at a location betweenthe bottom surface of the biosensor 400 and the tip of the needle 430,as can be seen in FIG. 4B. In addition, the legs 422 a-b allow thecentral feature 420 to collapse against the bottom surface of thebiosensor 400 when it is applied to a wearer's skin

Referring now to FIGS. 5A-5B, FIGS. 5A-5B show an example sensoralignment and retention feature 520 (or just “retention feature”)according to this disclosure. In this example, the retention feature 520is coupled to a pad 510 that may be affixed during manufacturing to alower surface of a biosensor, such as biosensor 500 shown in FIG. 5B.Similar to the example shown in FIG. 4A, the retention feature 520 inthis example has a central feature 524 that engages with and encirclesthe insertion needle 530 of a biosensor 500. In the example shown inFIG. 5A, the central feature 524 does not yet have an opening cut in itto accommodate the insertion needle 530; however, the opening may be cutat any suitable point during the manufacturing process. Alternatively,in some examples, the opening may be created when an insertion needle isinserted through the CGM and retention feature, which may occur duringthe manufacturing process or at the time the CGM is applied by thewearer.

In addition to the central feature 524, the example retention feature520 includes two legs 522 a-b. Similar to the example shown in FIG. 4A,each leg 522 a-b has two ends, one of which is coupled to a pad 510, orif no pad is used, to a ring or other feature that may be affixed to thebottom surface of a biosensor 500. The other end of each leg 522 a-b iscoupled to the central feature 524. In this example, the legs 522 a-battach at opposite sides of the central feature 524 and each then coupleat a respective point on the pad 510 substantially 90 degrees offsetaround the central feature 424. As discussed above with respect to FIGS.4A and 4B, any suitable number of legs may be employed in differentexamples. For example, the retention feature 520 shown in FIG. 5A may bemodified to add two additional legs, each of which may couple to thecentral feature 524 such that each of the legs couples at positions 90degrees offset from each other, and the other ends of each leg likewisecouple at positions 90 degrees offset from each other on the pad 510.

The two legs 522 a-b in this example allow the central feature 524 toextend away from the biosensor 500 to engage with and encircle theinsertion needle 530 at a location between the bottom surface of thebiosensor 500 and the tip of the needle 530, as can be seen in FIG. 5B.In addition, the legs 522 a-b allow the central feature 520 to collapseagainst the bottom surface of the biosensor 500 when it is applied to awearer's skin. Thus, this example retention feature 520 providesalignment and retention of a sensor wire within a hollow insertionneedle 530 used to apply an invasive biosensor 500.

Referring now to FIG. 6, FIG. 6 shows an exploded view of an example padand sensor alignment and retention assembly 600. The example alignmentand retention assembly 600 includes four components that may beseparately manufactured and assembled to provide sensor alignment andretention for an invasive biosensor. The assembly 600 includes aretention feature 610, a top-layer adhesive 620, a backing material 630,and a bottom-layer adhesive 640. In this example, the retention feature610 has the same configuration as the retention feature 520 shown inFIGS. 5A-5B, which has two legs and a central feature. The retentionfeature 610 in this example is separately manufactured from a piece ofpolyurethane foam by cutting away portions of the foam to form the legs,central feature, and perimeter ring.

The top-layer adhesive 620 is a PSA that is applied to the backingmaterial 630 during the manufacturing process. The PSA is applied to theperimeter of the retention feature 610 and is also applied to portionsof the backing material 630 to provide adhesion between the backingmaterial 630 and the bottom surface of a biosensor housing. In thisexample, the top-layer adhesive 620 is provided as a single piece oftwo-sided tape, but in some examples may be sprayed onto the backingmaterial 630 or may include multiple pieces of tape. Further, thetop-layer adhesive 620 may be applied at any suitable locations on thebacking material 630 to provide adhesion between the backing material630 and the retention feature 610, as well as between the backingmaterial 630 and the bottom surface of a biosensor housing.

The backing material 630 in this example is constructed of apolyurethane-coated fabric; however, any suitable material may beemployed, such as cloths, foams, etc. In this example, the backingmaterial 630 has been cut from a sheet of material into a shapecorresponding to the shape of a biosensor's housing and with a hole tocorrespond to the retention feature.

The bottom-layer adhesive 640 is a PSA that is applied to the backingmaterial 630 and is intended to adhere the backing material 630, andthereby the invasive biosensor, to a wearer's skin. Thus, thebottom-layer adhesive 640 comprises an adhesive suitable for long-termcontact with a person's skin. Such an adhesive may be water and humidityresistant. In this example, the adhesive comprises a two-sided tape thathas been cut to a shape corresponding to the shape of the backingmaterial 630. In some examples, the bottom-layer adhesive 640 maycomprise another type of adhesive, such as a liquid that may be sprayedonto the backing material 630 or may include multiple pieces of tape.

To create the example assembly 600 shown in FIG. 6, the top-layeradhesive 620 is applied to one side of the backing material 630. Theretention feature 610 is then pressed against a location on backingmaterial 630 corresponding to the top-layer adhesive 620 and the holeformed in the backing material 630. The bottom-layer adhesive 640 isthen applied to the other side of the backing material 630. It should beappreciated that the ordering of the steps described above may varyaccording to different manufacturing processes. In some examples, othersteps may be included, steps described above may be omitted, or thesteps may be performed in a different order. For example, the backingmaterial 630, with the top-layer adhesive 620 and retention feature 610,may be adhered to a bottom surface of an invasive biosensor before thebottom-layer is applied. Still further variations are within the scopeof the present disclosure.

Referring now to FIG. 7, FIG. 7 shows an exploded view of an example padand sensor alignment and retention assembly 700. In this example, theassembly includes a backing material 720 with a top-layer adhesive 710and a bottom-layer adhesive 730.

Unlike the example assembly 600 shown in FIG. 6, in this example, theassembly has a retention feature 722 formed from the same piece ofmaterial as the backing material 720. Thus, rather than having twoseparate pieces, the backing material and the retention feature areformed from the same piece of material. A top-layer adhesive 710 maythen be applied to one side of the backing material 720 to adhere thebacking material to a bottom surface of an invasive biosensor. Abottom-layer adhesive 730 may be applied to the other side of thebacking material 720 to adhere the backing material 720 to a wearer'sskin. Suitable materials for the backing material 720 and retentionfeature 722 are described above, as are suitable adhesives for thetop-layer and bottom-layer adhesives 710, 730.

Referring now to FIGS. 8A-8B, FIGS. 8A-8B illustrate an exampletechnique 800 for applying a retention feature to an invasive biosensor.In this example, an example backing material (or pad) and sensoralignment and retention assembly similar to the assembly 600 shown inFIG. 6 is employed, though any other suitable assembly according to thisdisclosure may be used. Specifically, the technique 800 described withrespect to FIGS. 8A-8B relates to assemblies with distinct pads andretention features that are formed from different pieces of materials.

At block 810 a of FIG. 8A, illustrated with corresponding diagram 810 b,an adhesive 852 is applied to a biosensor housing 850. In this example,the top-layer adhesive 852 is a two-sided tape that is cut into a shapecorresponding to the shape of the bottom surface of the housing 850 andis pressed against the bottom surface of the housing 850. In someexamples, however, the adhesive 852 may be sprayed onto the housing, thehousing 850 may be dipped into an adhesive, or any other suitabletechnique may be used to apply an adhesive to the bottom surface of thehousing 850, such as heat staking to fuse the components together. Inthis example, the adhesive 852 is applied to the entire bottom surfaceof the housing; however, in some examples, the adhesive 852 may beapplied at a location corresponding to a retention feature 854 and atone or more other locations corresponding to a pad 856 or multiple pads.

At block 820 a, illustrated with corresponding diagram 820 b, aretention feature 854 is affixed to the bottom surface of the housing850 by pressing it against the adhesive 852. The retention feature 854is applied at a location corresponding to where a sensor wire and needleextend (or will extend) from the bottom surface of the housing 850, suchthat an opening on the retention feature 934 are aligned with the exitpoint of the sensor wire from the bottom surface of the housing 850.

At block 830 a, illustrated with corresponding diagram 830 b, a pad 856is affixed to the bottom surface of the housing 850 by pressing itagainst the adhesive 852. In this example, the retention feature 854 isnot separately adhered to the pad 856, but instead, the pad 856 has acut-out corresponding to the retention feature so that the pad 856 mayadhere to the housing 850 while not interfering with the retentionfeature's function.

After the pad 856 has been affixed to the bottom surface of the housing850, an adhesive may be applied to the exposed surface of the pad 856 toallow the pad 856 to be affixed to a wearer's skin Such additionaladhesive may be applied before the pad 856 is affixed to the housing 850or afterwards. Further, such additional adhesive may be applied as atape or may be sprayed onto the pad 856.

It should be appreciated that the ordering of the steps described abovewith respect to the method 800 of FIG. 8A may vary according todifferent manufacturing processes. In some examples, other steps may beincluded, steps described above may be omitted, or the steps may beperformed in a different order. For example, the adhesive 852 may beseparately applied to the retention feature 854 and the pad 856, whichmay be pressed against the bottom surface of the housing 850. Stillfurther variations are within the scope of the present disclosure.

Referring now to FIGS. 9A-9B, FIGS. 9A-9B illustrate an exampletechnique 900 for applying a retention feature to an invasive biosensor.In this example, an example pad and sensor alignment and retentionassembly similar to the assembly 600 shown in FIG. 6 is employed, thoughany other suitable assembly according to this disclosure may be used.Specifically, the technique 900 described with respect to FIGS. 9A-9Brelates to assemblies with distinct pads and retention features that areformed from different pieces of materials.

At block 910 a, illustrated with corresponding diagram 910 b, aretention feature 934 is affixed to the bottom surface of the housing930 by applying an adhesive to a portion of the retention feature 932and pressing the retention feature 934 against the housing. For example,referring again to the retention feature 600 shown in FIG. 6, anadhesive 932 may be applied to one side of the ring encircling the legsand center feature of the retention feature. Thus, the retention feature934 may be applied to the housing while allowing the legs and centerfeature to extend away from the housing 930 and engage with an insertionneedle. After the adhesive 932 has been applied to the retention feature934, it may be affixed to the housing 930 by pressing it against thehousing 930. The retention feature 934 is applied to the housing 930 ata location corresponding to where a sensor wire and needle extend (orwill extend) from the bottom surface of the housing 930, and such that ahole or slit(s) on the retention feature 934 are aligned with the exitpoint of the sensor wire from the bottom surface of the housing 930.

At block 920 a, illustrated with corresponding diagram 920 b, a pad 938is affixed to the bottom surface of the housing 930 by applying anadhesive 936 to one side of the pad 938, and pressing it against thebottom surface of the housing 930. In this example, the pad 938 has acut-out corresponding to the retention feature 934 so that the pad mayadhere to the housing 930 while not interfering with the retentionfeature's function.

After the pad 938 has been affixed to the bottom surface of the housing930, an adhesive may be applied to the exposed surface of the pad 938 toallow the pad 938 to be affixed to a wearer's skin. Such additionaladhesive may be applied before the pad 938 is affixed to the housing 930or afterwards. Further, such additional adhesive may be applied as atape or may be sprayed onto the pad 938.

It should be appreciated that the ordering of the steps described abovewith respect to the method 900 of FIG. 9A may vary according todifferent manufacturing processes. In some examples, other steps may beincluded, steps described above may be omitted, or the steps may beperformed in a different order. For example, the adhesive 932 may beapplied to the housing 930, and the retention feature 944 may thenadhered to the housing 930. Similarly, the adhesive 936 may be appliedto the housing 930, and the pad 938 may then be pressed against thebottom surface of the housing 850. Still further variations are withinthe scope of the present disclosure.

Referring now to FIGS. 10A-10B, FIGS. 10A-10B illustrate an exampletechnique 1000 for applying a retention feature to an invasivebiosensor. In this example, an example pad and sensor alignment andretention assembly similar to the assembly 600 shown in FIG. 6 isemployed, though any other suitable assembly according to thisdisclosure may be used. Specifically, the technique 1000 described withrespect to FIGS. 10A-10B relates to assemblies with distinct pads andretention features that are formed from different pieces of materials.

At block 1010 a, a pad 1034 is affixed to the bottom surface of thehousing 930. The adhesive 1032 may be applied to the housing 1030 or itmay be applied to the pad 1034. The pad 1034 is then affixed to thehousing 1030 by pressing it against the bottom surface of the housing1030.

At block 1020 a, illustrated with corresponding diagrams 1020 b and 1020c, a retention feature is applied to the biosensor. With respect toexample 1020 b, the pad 1034 is shaped to correspond to a shape of thehousing 1030, though it has portions that extend beyond the edges of thehousing 1030. In addition, while the pad 1034 has an opening cut in itto accommodate a sensor wire and insertion needle, the retention featureis affixed to the pad 1034, rather than the housing 1030. In thisexample, an adhesive is applied to the bottom surface of the pad, suchas an adhesive suitable for adhering the pad 1034 to a wearer's skin.The retention feature 1036 is then pressed against the pad and isaffixed by the adhesive.

With respect to example 1020 c, a pad 1035 is shaped to correspond to ashape of the housing 1030, though it has portions that extend beyond theedges of the housing 1030. In addition, the pad 1035 has a portion cutout of it to allow the retention feature 1036 to be affixed directly tothe housing 1030 by the adhesive 1032. The retention feature 1036 isinserted into the cut-out in the pad 1034, pressed against the housing1030 and is affixed by the adhesive 1032.

The retention feature 1036 is applied to the housing 1030 at a locationcorresponding to where a sensor wire and needle extend (or will extend)from the bottom surface of the housing 1030, and such that an opening onthe retention feature 1036 are aligned with the exit point of the sensorwire from the bottom surface of the housing 1030. Further, after the pad1034 has been affixed to the bottom surface of the housing 1030, anadhesive may be applied to the exposed surface of the pad 1034 to allowthe pad 1034 to be affixed to a wearer's skin. Such additional adhesivemay be applied before the pad 1034 is affixed to the housing 1030 orafterwards. Further, such additional adhesive may be applied as a tapeor may be sprayed onto the pad 1034.

Referring now to FIGS. 11a-11b , FIGS. 11a-b illustrate an examplesensor alignment and retention feature 1110. In this example, theretention feature 1110 is a disk of material with an opening cut into itto allow an insertion needle and sensor wire to be inserted through theretention feature 1110. The retention feature 1110 in this example,unlike the previous examples, is not affixed to the housing or a pad,but instead is positioned along the length of the insertion needle 1120between the bottom of the invasive sensor 1100 and the tip of the needle1120 and held in place through the tight fit of the needle through thematerial. Thus, the retention feature 1110 engages with and encirclesthe needle 1120, thereby maintaining the sensor wire within the hollowportion of the sensor wire. While in this example, the retention feature1110 has a circular shape, however, any suitable shape for the retentionfeature may be employed.

FIG. 11a illustrates the retention feature 1110 installed on theinsertion needle before the biosensor is affixed to a wearer. FIG. 11billustrates how the retention feature 1110 collapses against the bottomsurface of the biosensor 1100 after the biosensor has been affixed to awearer. This example retention feature 1110 slides upwards along theneedle 1120 until it is pressed against the underside of the biosensor.

Referring now to FIGS. 12a-12b , FIGS. 12a-b illustrate an examplesensor alignment and retention feature 1244. Shown in FIG. 12a is abiosensor 1200 having a housing 1210 to which a pad 1242 is adhered byan adhesive 1240. A sensor wire 1230 extends through a cavity defined inthe housing 1210 and down through a hole in the bottom surface of thehousing 1210. In addition, an insertion needle 1220 has been insertedthrough a hole defined in the upper surface of the housing 1210, througha cavity defined between the holes in the upper surface and lowersurface of the housing 1210, and out through the bottom of the biosensor1200. As is shown, a portion of the sensor 1230 is positioned within ahollow portion of the insertion needle 1220 such that the two areco-axially aligned.

In this example, a retention feature 1244 is shown that is similar tothe retention feature 1110 shown in FIGS. 11A-11B. Specifically, theretention feature 1244 is engaged with an insertion needle 1220, but isnot otherwise affixed to the biosensor 1200. Instead, the retentionfeature 1244, prior to the biosensor 1200 being affixed to a wearer, ispositioned on the needle between the pad 1242 and the tip of the needle1220.

FIG. 12b illustrates the biosensor 1200 after it has been applied to awearer and the insertion 1220 needle has been withdrawn. The retentionfeature 1244 has been forced upward into contact with the pad 1242, andthe sensor wire 1230 has been left in place within the wearer's skin.The retention 1244 feature can adhere to the bottom of the pad 1242 asthe underside of 1242 is coated with adhesive to attach to the skin.Thus, at a later time when the biosensor 1200 is removed, the retentionfeature 1244 will be removed with the biosensor 1200.

Referring now to FIGS. 13a-13b , FIGS. 13a-b illustrate an examplesensor alignment and retention feature 1344. Shown in FIG. 13a is abiosensor 1300 having a housing 1310 to which a pad 1342 is adhered byan adhesive 1340. A sensor wire 1330 extends through a cavity defined inthe housing and down through a hole in the bottom surface of the housing1330. In addition, an insertion needle 1320 has been inserted through ahole defined in the upper surface of the housing 1310, through a cavitydefined between the holes in the upper surface and lower surface of thehousing 1310, and out through the bottom of the biosensor 1300. As isshown, a portion of the sensor 1330 is positioned within a hollowportion of the insertion needle 1320 such that the two are co-axiallyaligned.

This example is similar to the example shown in FIGS. 12A-12B, however,as can be seen, the pad 1342 in FIGS. 13A-13B has a portion cut out toallow the retention feature to slide up against the housing and lieflush with the pad 1342. Thus, after the biosensor 1300 has been affixedto a wearer's skin and the insertion needle 1320 has been removed, theretention feature 1344 has slide upwards into the cut out area withinthe pad 1342, allowing it to lie flush with the pad 1342, and to adhereit to the housing 1310 through the adhesive 1340. Thus, at a later timewhen the biosensor 1300 is removed, the retention feature 1344 will beremoved with the biosensor 1300.

Referring now to FIGS. 14A-14C, FIGS. 14A-14C show an example sensoralignment and retention feature 1430 according to this disclosure. Inthis example, an invasive biosensor 1400 includes a sensor wire 1410that extends out from a bottom surface of the biosensor 1400. Aninsertion needle 1420 has been inserted through the biosensor andaligned co-axially with the sensor wire 1410. The retention feature 1430in this example has a shape similar to a stopper having an openingformed through it to accommodate the insertion needle 1430, and iscomposed of an elastomeric material such as silicone rubber or other.

The retention feature 1430 has a flat bottom surface 1432 that willbecome flush with the bottom surface of the biosensor 1400 once thebiosensor 1400 has been affixed to a wearer's skin. As can be seen, andsimilar to the disk 1344 shown in FIGS. 13A-13B, the retention feature1410 is attached to a portion of the insertion needle through aninterference fit, but is not otherwise attached to the biosensor 1400 asshown in FIGS. 14A-14B. When the biosensor 1400 is applied to a wearer'sskin, the retention feature 1430 slides upwards along the needle 1420and into a cavity 1402 defined in the underside of the biosensor 1400,thereby allowing the retention feature 1430 to collapse into and beretained by the biosensor 1400, as can be seen in FIG. 14C.

Referring now to FIG. 15, FIG. 15 shows an example method 1500 forinvasive biosensor alignment and retention according to this disclosure.The method 1500 will be described with respect to the example retentionfeature 1430 shown in FIGS. 14A-14B; however, any suitable retentionfeature or means for according to this disclosure may be employedaccording to different examples.

At block 1510, a biosensor is obtained. In this example, the biosensoris obtain by constructing a biosensor. The biosensor is constructed byobtaining a housing having a first surface defining a first opening, anda second surface opposite the first surface defining a second opening,the first and second openings defining a substantially unobstructedpathway through the housing.

After obtaining the housing, a biosensor wire is positioned within thehousing and oriented so that a first portion of the biosensor wireextends through the first opening and out of the housing. A hollowinsertion needle is then inserted into and through the unobstructedpathway from the second opening and through the first opening such thatthe hollow insertion needle at least partially encircles the portion ofthe biosensor wire that extends out of the housing.

At block 1520, a retention feature 1430 is obtained. For example, theretention feature 1430 may be received during a manufacturing process,such as by an automated machine operating as a part of an assembly line.In one example, the retention feature 1430 is picked by a robotic arm.In some examples, a retention feature cd1430 may be provided in an uncutsheet of material having one or more preformed retention features 1430.

At block 1520, the retention feature 1430 is attached to the needle 1420of a biosensor 1400. In this example, and as described above, the needle1420 is inserted through the housing of a biosensor 1430, such asthrough a hole in the upper surface of the biosensor 1400, through acavity formed within the biosensor 1420, and out through a hole in thelower surface of the biosensor 1400. Further, the needle 1420 isco-axially aligned with a sensor wire 1410 that is mounted within thebiosensor, but extends downward through a hole in the bottom surface ofthe biosensor 1400 and is positioned within a hollow portion of theneedle 1420.

In this example, an opening formed in the retention feature 1430 isaligned with the needle 1420, and the retention feature 1430 is pressedonto the needle 1420 and slid along a portion of the length of theneedle 1420. The distance the retention feature 1430 is slid along thelength of the needle 1420 may vary according to different examples,however, in this example, the retention feature 1430 is ultimatelypositioned to allow approximately 1-5 mm of the needle 1420, includingthe sharp tip of the needle 1420, to protrude from the retention feature1430. In some examples, the retention feature 1430 may be positionedsuch that no portion of the needle 1420 protrudes from the retentionfeature 1430, but the sharp tip of the needle 1420 is substantiallyaligned with the flat bottom surface 1432 of the retention feature 1430.Such positioning may provide sensor alignment and retentionfunctionality and may also shield the end of the needle 1420 to preventit unintentionally contacting the wearer or some other object prior tobeing inserted into the wearer's skin.

In this example, the needle 1420 is pressed through a hole formed in theretention feature 1430; however, in some examples, a retention featuremay be formed without such a hole. Thus, the needle may be pressedthrough the retention feature to form a hole and to couple the retentionfeature to the needle.

In some examples, at block 1520 a retention feature 1430 may be applied,as well as other components, such as one or more adhesives or a pad,such as described above with respect to FIGS. 8A-8B, 9A-9B, or 10A-10B.

In some examples, such as with respect to the examples shown in FIGS.11A-11B, 12A-12B, or 13A-13B, the retention feature 1430 discussed abovemay be replaced with a disk, such as the disk 1110 shown in FIGS.11A-11B. In addition, one or more pads or adhesives may be applied, suchas shown in FIGS. 12A-12B and 13A-13B, as discussed above with respectto the methods 800-1000 of FIGS. 8A-8B, 9A-9B, or 10A-10B.

Referring now to FIG. 16, FIG. 16 shows a method 1600 for applying awearable biosensor having a biosensor retention feature. The examplemethod of FIG. 16 will be described with respect to the examplebiosensor 1100 shown in FIGS. 11A-11B; however, any suitable wearablebiosensor and biosensor retention feature according to this disclosuremay be employed.

At block 1610, a wearer obtains a wearable biosensor 1100 having abiosensor retention feature 1110 encircling and contacting a hollowinsertion needle inserted through the housing of the biosensor andco-axially aligned with a portion of a sensor wire extending from thehousing of the biosensor.

At block 1620, the wearer applies the wearable biosensor 1100 byinserting the hollow insertion needle 1120 into the wearer's skinthrough a puncture at the desired location on the wearer's skin. Thewearer inserts the biosensor wire through the puncture as well, takingadvantage of the coaxial alignment between the biosensor wire and thehollow insertion needle 1120, by pressing the wearable biosensor'shousing against the wearer's skin, thereby collapsing the biosensorretention feature against the housing.

At block 1630, the wearer withdraws the insertion needle from thepuncture and the housing, leaving the wearable biosensor affixed to thewearer's skin and the biosensor wire inserted through the patient'sskin.

The foregoing description of some examples has been presented only forthe purpose of illustration and description and is not intended to beexhaustive or to limit the disclosure to the precise forms disclosed.Numerous modifications and adaptations thereof will be apparent to thoseskilled in the art without departing from the spirit and scope of thedisclosure.

Reference herein to an example or implementation means that a particularfeature, structure, operation, or other characteristic described inconnection with the example may be included in at least oneimplementation of the disclosure. The disclosure is not restricted tothe particular examples or implementations described as such. Theappearance of the phrases “in one example,” “in an example,” “in oneimplementation,” or “in an implementation,” or variations of the same invarious places in the specification does not necessarily refer to thesame example or implementation. Any particular feature, structure,operation, or other characteristic described in this specification inrelation to one example or implementation may be combined with otherfeatures, structures, operations, or other characteristics described inrespect of any other example or implementation.

Use herein of the word “or” is intended to cover inclusive and exclusiveOR conditions. In other words, A or B or C includes any or all of thefollowing alternative combinations as appropriate for a particularusage: A alone; B alone; C alone; A and B only; A and C only; B and Conly; and A and B and C.

That which is claimed is:
 1. A wearable biosensor device comprising: a housing comprising: a first surface defining a first opening, the first surface configured to be coupled to a skin of a wearer, and a second surface opposite the first surface, the second surface defining a second opening, the first and second openings defining a substantially unobstructed pathway through the housing; a biosensor wire partially disposed within the housing and having an exterior portion extending through the first opening; a hollow insertion needle positioned within the pathway and extending through the first opening, the hollow insertion needle at least partially encircling the biosensor wire; and a biosensor retention feature collapsible against the first surface of the housing, the biosensor retention feature encircling and contacting the hollow insertion needle.
 2. The wearable biosensor device of claim 1, wherein the biosensor retention feature comprises a patch, an inner ring member, an outer ring member, and at least one flexible leg member coupling the inner ring member to the outer ring member, the inner ring member encircling and contacting the hollow insertion needle, the outer ring member affixed to the patch, and the patch affixed to the first surface of the housing.
 3. The wearable biosensor device of claim 2, wherein the biosensor retention feature comprises a plurality of flexible leg members coupling the inner ring member to the outer ring member, each of the flexible leg members attaching to the inner ring member at a respective first contact point and the outer ring member at a respective second contact point.
 4. The wearable biosensor device of claim 3, wherein the respective first and second contact points for at least one flexible leg member are offset from each other.
 5. The wearable biosensor device of claim 1, wherein the biosensor retention feature comprises a disk defining a hole, the insertion needle and biosensor wire extending through the hole in the disk, the disk spaced apart from the first surface of the housing.
 6. The wearable biosensor device of claim 5, wherein the biosensor retention feature comprises a flexible material.
 7. The wearable biosensor device of claim 4, wherein the flexible material comprises a polyurethane foam material or a silicone material.
 8. The wearable biosensor device of claim 5, wherein the biosensor retention feature is adapted to enable the disk to slide along the hollow insertion needle and into contact with the first surface of the housing in response to a force applied to a bottom surface of the disk.
 9. The wearable biosensor device of claim 1, wherein the biosensor retention feature comprises a stopper-shaped member defining a hole extending through the stopper-shaped member, the insertion needle and biosensor wire extending through the hole in the stopper-shaped member.
 10. The wearable biosensor device of claim 9, wherein the stopper-shaped member is configured to slide along the hollow insertion needle and into an opening defined in the first surface of the housing in response to a force applied to a bottom surface of the stopper-shaped member.
 11. The wearable biosensor device of claim 1, further comprising a pad affixed to the first surface of the housing, the retention feature coupled to the pad and extending away from the pad.
 12. The wearable biosensor device of claim 1, further comprising a pad affixed to the first surface of the housing, the retention feature not coupled to the pad, the pad defining a cutout portion corresponding to the retention feature, the retention feature configured to collapse against the housing and into the cutout portion defined by the pad.
 13. A wearable biosensor device comprising: a housing comprising: a first surface defining a first opening, the first surface configured to be coupled to a skin of a wearer, and a second surface opposite the first surface, the second surface defining a second opening, the first and second openings defining a substantially unobstructed pathway through the housing; a biosensor wire partially disposed within the housing and having an exterior portion extending through the first opening; a hollow insertion needle positioned within the pathway and extending through the first opening coaxially aligned with the exterior portion of the biosensor, the hollow insertion needle at least partially encircling the exterior portion of the biosensor wire; and means for maintaining coaxial alignment between the hollow insertion needle and the biosensor wire coupled to a portion of the hollow insertion needle coaxially aligned with the exterior portion of the biosensor wire.
 14. The wearable biosensor device of claim 13, wherein the means for maintaining coaxial alignment includes at least one flexible leg.
 15. The wearable biosensor device of claim 13, wherein the means for maintaining coaxial alignment is spaced apart from the housing. 